(a) Compare and contrast 'preservation' and 'conservation' of plants. Explain the importance of both in the utilization and…

(a) Preservation versus Conservation of Plants Preservation means protecting plants and ecosystems from human use, keeping them as untouched as possible (strict nature reserves, core zones, and seed storage that is not used). Conservation, in the IUCN sense (World Conservation Strategy, 1980), is the management of the biosphere so that it yields the greatest sustainable benefit to present generations while maintaining its potential for future ones. It includes preservation, sustainable use, restoration and enhancement.

Contrast:

• Objective: preservation aims at static protection of a species or area, while conservation is dynamic management for continued benefit.
• Human use: preservation excludes use, while conservation permits regulated use (sustainable harvest of medicinal plants, agroforestry).
• Methods: preservation uses strictly protected areas, sacred groves and ex-situ storage; conservation adds in-situ management (biosphere reserves), restoration, ex-situ gene banks and sustainable utilisation.
• Philosophy: preservation values nature for its own sake; conservation values it as a resource (the Muir versus Pinchot debate).

Importance for utilisation: conservation sustains supplies of timber, medicinal plants, food crops and their wild relatives, which supply genes for breeding, such as wild rice Oryza nivara giving grassy stunt resistance. Gene banks (NBPGR, Svalbard), cryopreservation and botanical gardens keep material for future use.

Importance for management: both prevent extinction in hotspots (the Western Ghats, Himalaya, Indo-Burma, Sundaland in India), maintain ecosystem services, and guide policy: the Convention on Biological Diversity (1992), the Biological Diversity Act, 2002, the Wildlife (Protection) Act, 1972 and the PPV&FR Act, 2001. IUCN Red List categories guide priorities.

(b) Stages of Micropropagation and Its Advantages Micropropagation is the rapid clonal multiplication of plants from small explants (shoot tips, nodes, meristems) in vitro under aseptic conditions on a defined medium.

Stages (Murashige):

• Stage 0, preparation: selection of a healthy, disease-free, elite mother plant, often pre-treated.
• Stage I, initiation: surface-sterilised explants (shoot tip, axillary bud) are established aseptically on a medium such as MS.
• Stage II, multiplication: cytokinins (BAP, kinetin) induce axillary shoot proliferation, with repeated subculture, producing thousands of shoots.
• Stage III, rooting: shoots are transferred to a medium with auxin (IBA, NAA), usually with reduced salts and sugar, to form roots.
• Stage IV, hardening (acclimatisation): plantlets are moved to cocopeat or soil under high humidity (mist chamber, polybag), gradually exposed to normal humidity, then to the field.

Advantages over conventional propagation (seeds, cuttings, grafting): very rapid multiplication of millions of plants in small space and time, year-round; true-to-type clones of elite plants; disease-free plants through meristem culture (virus-free potato, banana, sugarcane); propagation of plants difficult by seeds or cuttings, such as orchids; germplasm storage and exchange (including cryopreservation); and no dependence on season. Limitations: cost, contamination, hyperhydricity and somaclonal variation. Examples: banana, potato, orchids, sugarcane.

(c) Androgenic Haploids: Technique and Applications Androgenic haploids are haploid plants (n) obtained from immature pollen (microspores), the male gametophyte, in culture. Guha and Maheshwari (1964) first produced them from Datura anthers.

Technique (anther or microspore culture): buds with anthers at the uninucleate microspore stage are selected, often given a cold pretreatment (4-8°C) and surface-sterilised. The anthers are excised and cultured on a medium (MS, N6 for rice, or the potato medium for cereals) with sucrose, and often auxin and cytokinin. Under dark incubation, microspores switch from pollen development to division, forming pollen embryoids or callus, which are moved to a regeneration medium to form haploid plantlets. Chromosomes are doubled with colchicine (or spontaneously) to give fertile, homozygous doubled haploids (DH).

Applications: homozygous pure lines in one generation instead of 6-8 generations of selfing, saving time; exposure of recessive mutations; use in mutation breeding, genetic mapping and transgenic homozygote production; and DH varieties in rice, wheat, barley, rapeseed (Brassica) and tobacco. They are different from gynogenic haploids, which arise from the egg/ovule.